a place that serves as the center of a group, as of militants or of persons holding a controversial viewpoint: The campus was a stronghold of liberalism.
Origin of stronghold
late Middle English word dating back to 1375–1425; see origin at strong, hold1
By the second half of the 13th century, the territories of the Crusader States had shrunk considerably and were limited to the small yet strategically vital coastal areas and strongholds like Tripoli, Acre, Tyre, Sidon, Haifa, and Tartus.
History of the Crusades: Origins, Politics, and Crusaders|Dattatreya Mandal|March 23, 2020|Realm of History
A Shiite stronghold wrapped in a Sunni explosive belt—not exactly a picture of stability.
The Nuclear Deal That Iran’s Regime Fears Most|Djavad Khadem|November 22, 2014|DAILY BEAST
In Diyarbakır, a PKK stronghold, protestors defied orders to remain indoors.
Kobani is Falling to ISIS in Syria. Kurd Protests Explode in Turkey.|Jamie Dettmer|October 10, 2014|DAILY BEAST
It still remains incredibly difficult for new comics and heroes to get a stronghold in the marketplace.
DC Comics’ Diversity Crisis: Why the Status Quo Rules|Liz Watson|July 20, 2014|DAILY BEAST
Aleppo has been a stronghold of the more legitimate opposition to Bashar al-Assad.
Why the Border Bigots Are Beating Obama|Michael Tomasky|July 9, 2014|DAILY BEAST
Several are dead and Western journalists taken hostage as open warfare erupts around pro-Russian stronghold of Slovyansk.